Members of the Anonymous hacktivist movement are claiming responsibility for taking down more than 40 secret child-pornography websites and leaking the names of more than 1,500 members of one of the illegal sites.

The Anonymous campaign began Oct. 14, when members of the hacktivist group found a cache of child-pornography websites while browsing a secret website called the Hidden Wiki, a guidebook to hundreds of underground websites invisible to search engines and regular Internet users. The hackers singled out Lolita City, a file-sharing site used by pedophiles, and leaked the names of the site’s 1,589 active members to Pastebin on Tuesday (Oct. 18), the Examiner reported.

Member of Anonymous deciding to hack a website whose stance they don’t agree with is by no means shocking news. In the past year, Anonymous-affiliated hackers have gone after the New York Stock Exchange, the Westboro Baptist Church, the Recording Industry Association of America and government sites in Malaysia, Egypt, Tunisia and Zimbabwe.

However, in targeting child pornography sites, and in explaining its methods of attack, these Anonymous-affiliated hackers have revealed a deeply disturbing side of the Internet unknown to most people.

The so-called “darknet,” from which this “Operation Darknet” hacking campaign takes its name, is any part of the Internet that is hidden from view — not just hard to reach, but deliberately concealed. In this instance, a darknet appears to have grown out of the free TOR routing service, which offers anonymous, encrypted Web browsing to any user.

The TOR-based darknet has reportedly grown into a private, encrypted constellation of websites offering a variety of shady and illegal services, from fake IDs and steroids to email hacking and tip on how to call in police raids as pranks. There’s even a hidden site called “The Last Box” that bills itself as an “Assassination Market.”

Only computers that have installed TOR browser plug-ins can access the TOR-based darknet, including its guidebook the Hidden Wiki, the security site Infosec Island reported.

In another Pastebin posting, the hackers explained that their campaign against the child pornography sites took root when they found a site listed on the Hidden Wiki called “Hard Candy,” which “was dedicated to links to child pornography.” The group delved deeper and discovered that nearly all of the pornography sites listed on the Hidden Wiki “shared a digital fingerprint with the shared hosting server at Freedom Hosting.”

The Anonymous-affiliated hackers then issued a warning to Freedom Hosting asking it to remove the child pornography links from its server. Freedom Hosting did not comply, so the group, at approximately 11:30 p.m. (CST) on Oct. 14 shutdown Freedom Hosting’s server. Freedom Hosting restored service the following day, but it was attacked and taken down again that night.

In its statement, the Anonymous members explained their goals and how they aim to achieve them through repeated pressure and consistent online attacks.

“The owners and operators at Freedom Hosting are openly supporting child pornography and enabling pedophiles to view innocent children, fueling their issues and putting children at risk of abduction, molestation, rape and death,” the message said. “For this, Freedom Hosting has been declared #OpDarknet Enemy Number One. By taking down Freedom Hosting, we are eliminating 40+ child pornography websites, among these is Lolita City, one of the largest child pornography websites to date containing more than 100 GB of child pornography. We will continue to not only crash Freedom Hosting’s server, but any other server we find to contain, promote, or support child pornography.”

The statement added a demand to Freedom Hosting and other Web servers hosting child pornography.

“Remove all child pornography content from your servers. Refuse to provide hosting services to any website dealing with child pornography. This statement is not just aimed at Freedom Hosting, but everyone on the Internet. It does not matter who you are, if we find you to be hosting, promoting, or supporting child pornography, you will become a target.”

The trail goes cold in looking for whoever is behind Freedom Hosting. The domain is currently offline; WHOIS domain-name lookups show that the registration for freedom-hosting.com expired on Aug. 7, and the registrar is holding the URL pending renewal.